Kat, along with? Carter-A259, is one of only two survivors from the original Noble Team. As a result, she shares a close bond with Carter. She is Noble Team's second-in-command, and described as being fiercely loyal to Carter and the rest of the team.

On April 22, 2552, Kat put together an? operation? to destroy a? CCS-class battlecruiser? maintaining position above a city.[1]? The operation was successful, but cost? Thom-293? his life, and Kat her right arm, which has since been replaced by a? robotic prosthetic.[4]? Kat clearly has no problem working with her prosthetic arm, as she moves it just as naturally as her previous biological one, even continuing to hold her? M6G pistol? in her dominant right hand.

Both? Carter-A259? and Kat took responsibility for the death of Thom, unable to admit that the death of the SPARTAN had been his own fault. Thom's place in Noble Team would be filled by? SPARTAN-B312? a few months later, just prior to the? Fall of Reach.

The Spartans of Noble Team participated in an operation to investigate a communications blackout at the Visegrád Relay, a mission which led to the first confrontation with Covenant forces on? Reach.[5]? During the operation, Kat recovered a data module containing? Laszlo Sorvad's "latchkey discovery" from the Relay's console and revealed that the Covenant had successfully deployed their forces on Reach.[5]? The discovery led the team to? Sword Base, currently under siege by Covenant forces and their? corvette.[6]? Kat and Noble Six engaged the Covenant forces on foot and repelled them off the site and the? airbase.

Intelligence gathered from Noble Six and? Jun-A266's reconnaissance mission lead to a large-scale UNSC assault on a Covenant-occupied site.[7]? Kat and Noble Six engaged Covenant forces on the groundside while other members of Noble Team provided aerial support. Noble Six assisted Kat in reconnaissance of the Covenant-occupied site, destroying? multiple aerial defenses? and unveiling a large Covenant installation code-named? Spire One.

At some point during the Fall of Reach, Kat and the remaining members of Noble Team assisted the UNSC in repelling the Covenant from civilian population centres. They reunited with Noble Six in? New Alexandria? and helped in the neutralization of Covenant communication jammers and the evacuation of ONI personnel.[9]? Soon, Noble Team was hailed by its supervisor,? Colonel? Urban Holland, and was ordered to destroy 'Sword Base'. The team was forced to enter a radiation bunker to shield them from the Covenant's glassing of New Alexandria. As Noble Team exited the elevator and ran towards the bunker, the? Sangheili Field Marshal? in a? Phantom? overhead shot her in the head with a? needle rifle, killing her instantly.[9]

Catherine was described as an inspired tactician and an exemplary combatant, but also a brilliant cryptanalyst and a hacker; allegedly, there was not been a system yet that she had been unable to crack. According to? ColonelUrban Holland, she had a habit of occasionally investigating classified Intel more than her superiors would have liked her to. Her ability to acquire and digest information has been described as "supernatural"; more than once, she had been able to read a situation, working with information many others would find overly limited.[1]

Much like Carter, Kat blamed herself for? Thom-293's death while it was apparent that neither was responsible; according to Colonel Urban Holland, Thom died because he when he went into the? CCS-class battlecruiser? that Kat was originally supposed to destroy before being injured by himself rather than waiting for backup, although Holland was technically incorrect in that case as the SPARTAN had no choice at that time due to the limited amount of time left before the MFDD detonated.[1]

Kat's death can be attributed due to a fatal lack of situational awareness. Like the loss of her right arm in a? previous operation, Kat underestimated the gravity of her situation and failed to initiate her armor's shielding system.[11]However, another explanation could be that excess radiation from the nearby Covenant glassing shorted out her shields, as she may have been exposed to the radiation longer than the other members of Noble Team. This is supported as she was temporarily blinded. Her trademark curiosity could also be blamed, as she was preoccupied at the time with understanding new uncharacteristic orders from Holland. Trading questions with Carter as to Holland's motives, she was too lost in her own mind as she analyzed this new information to focus on the present. Another reason is that Kat, having to hastily flee to a radiation bunker, did not have sufficient time to turn on her shields. The event was also her first glassing, perhaps suggesting the shock of the events caused her to forget to initiate her armor's shielding system.